Tanning of hides and skins



' hides; that of sulfuric acid,"according to Patented May 1, 1923; i

TANNING or nrnns'aNnsxlNs.

No Drawing.

To all whom it may concern:

Be it known that PIERRE J ULIEN CLEMENT MAneoTToN, a citizen of the Republic of France, and resident of Niort, France (post-'- oflice'address Niort, Deux Sevres), have invented 'new and useful Improvements in the Tanning of Hides and Skins, whichimprovements are fully set forth in the following'specification.

The present invention relates to the tanning of hidesand skins, and morezespe cially to .hides' intended to be used in, the manufacture of gloves, by a series of operations which enable the tanning to be efi'ected in an extremely short time; the

hides having first been subjected to working in a stream and tawed, and having been fleshed and pressed in the white.

To efi'ectthe' tanning of dehaired hides, they are passed, as subsequently explained, into a bath consisting of chromic acid, sulfuric acid and water. The object of the sulfuric acid is to activate the solution of.

chromic acid and to facilitate the penetration of the bathinto the interior of'the.

hides. The proportion of chromic acid may be varied according .tothe .weight of the the weight of chromic acid introduced into the bath. As regards the quantity of water,

this is constant whatever'the weight or thegrain of the hides to be treated. For eX- ample, the following proportions may be adopted: s

For 50 grams of dehaired hides,

Cromic acid; 2grams. Sulfuric acid Qcubic centimeters. Water 3liters. (This quantity of water will be used whatever may be. the weight and size of the dehaired hides.) I

Ewampl l. Bath for a small dehaired hide of 500 grams.

20 grams chromic acid. 20 cc. sulfuric acid. (These quantities may vary.)

3 liters water. (Constant quantity.)

Example 2. Bath for a large dehaired hide. 40 grams chromic acid. 4.0 cc. sulfuric acid. (These quantities may vary.)

3 liters water. (Constant quantity.)

Application filed Ju1y26, 1921. Serial No. 487,622.

- i The bath is contained ina'suitable fulling' Afr 'r some PI RRE UL EN oLnMENr maeorroN, or Nronnr nANonl tank or vessel, into. which the. dehaired hides. I are also introduced; andthis tank, which is I constructed to be rendered waterstightwhen 1 closed, is then rotated by-any desired means,

its rotary movement" causing the hides to slide one upon another and to strike heavily against the wallspof, the tank. Inconsequence, the bath liquid-is alternately -ab--v sorbed by and expelled from thehides, thus eflectingan energetic fulling action which is assisted by the impact of the hides against the tank. walls. I p I.

The hides remain in the fulling tank until completely penetrated by the liquid, which condition-canv be ascertained by makin' ,in-

cisions in the hides which shouldzbe ye low all theWay through. They are thereupon removedfrom the tank and allowed-toe drip,

and are then nailed on frames'which are if placed in a reaction chamber wherein the chromic acid in the hides. isftransformed into sulfate of chromlum sesquioxide, 1n-

order" to effect the tanning. In this chamber they are enveloped in an atmosphere of sulfurous acid gas which, since it is heavier I than air, is kept 1n motion by means .of a.

.fan; and they are allowed to remain therein until the reduction is complete, that isv to -Z sayuntil they have turned blue'all the way through, whichcan be'ascertained by means of incisions. Whenthe-treatment is. con: f

cluded,-air is blowninto the chamber. to drive out thesulfurous acid gas,-and the hides are nexttreated to. neutralize the sulfurous acid combinedin their interior, so asto prevent themfrom becoming corroded.

For this purpose, a heated current of. air' is caused to pass throughv atank partly filled with ammonia in solution, the air taking up the ammonia vapors and then flowing into the reaction chamber whereitenvelopesthe, V hides. The treatment is continuedunitlthe hides are neutralized or even slightly-basic, whereupon the chamber is again-blownout and the hides Withdrawn therefrom and washed in order to remove the ammonia. I

After washing, they are passed through a wringlng machln'eto remove the excess water, and are-then again nailed upon frames and replaced in the reaction CllELIIlber; by which time they have been rendered unsusceptible to above treatments.

The hides are next subjectedto a second tanning action in order to render them very putrefaction, because of the i v coholisvaporizedby'tlie'heat and carries off the water with it, leaving only the oil'in the supple; this supplemental tanning action or partial charn'oising being effected with oil and being very light only. It can be carried out very easily in, consequence of the small content. of sulfate efchroininm s'escpuiox'ide In order to effect the imrnein the hides. diate penetration of the oil into the interior of the hides, ordinary denatured alcohol is used; the hides being placed in the reaction chamber and subjected to a Current of hot air whichhas been caused'to pass through a tank half fullof alcohol. T heal cohol vapors,

in passing. through the chamber, are absorbed by the water-in the interior of the hldes and thus impregnate the latter; and to'prevent the vaporstrom condensing in the interior of the chamber, the temperature thereof is "kept at 30 C. Condensation may, however,

be' e'fi'ected I after the vapors have left the chamber, and the alcohol thus recoveredmay be used again.

lVhen the hides have been thoroughly impregnated'with the alcohol, the operation is interior of the hides; this oil'being oxidized in the presence of the chromium 'sesquioxide and efiectinga freshtannin'g action which constitutes a partialcha'rnoi'sing The'hid'es are nowlett for a'n'ho'ur in the reactionch'amber'and' th'en removed from the frames a'ndtranst'erredto an oil press, whereafter they are degreased, then scraped'again', wrung and finally nailed to a drying floor.

It'is thus possible to effect the tanning" of hides in a very short space oftim'e; and' the leatlier'thereby obtained is much finer than chamois,the grain'is' closerand the hide less s y,

the tanning being also more thorough since the hides are tanned t'wice, first with chromic acid'and' then with oil.-

What I claim and desire to secure by Letters Patent is 1. A process of tanning, comprising the 'stepsot subjecting the dehaired skins to" the action of a" tanning bath containing 'ohromic acid; treating the skins with sulfurousacid gas in a closed receptacle to transform the chrom 1c acid into sulfate of chromium sesquioxide; subjecting them to the action of amm'o'niacal' vapors to force out the sulfurous acid gas ;-washing the skin with water until the ammonia is removed, and then expelling the excess water then subjecting them-to-the action of alcohol vapors; submerging the skins in oil; evaporating the alcohol from the skins and leaving the oil' therein to be oxidized in the presence of the chromium sesquio'xide and to eitect a fresh tanning actlon; and finally dryingthe skins.

2. In a process of tanning, the steps of subjecting the dehaired skins tothe action of a tanning bath containing chromic me;

then treating the skins with a substance which will convert the chromic acid into chromium sesquioxide; and then treating the skins with oil, thereby to oxidize the oil in the'presence or" the chromium sequioxide and to effect a fresh tanning'action.

3. In a process of tanning, the steps of subjecting the dehaired skins to'the action of a tanning bath containing chromic'acid;

then treatingthe'damp skins first with $111- turous 2tC1(lLHd then with ammonia; removlng the ammonia"; and sub ectlng the SklDS 'to a fresh tanning action with oil.

A. In a process of tanning, the steps of subjecting the dehaired skins to the action of a tanning bath containing chromic acid;

then treating the dampskins first with sulfurous acid gas and'then with ammoniacal vapors entrained 1n a1r;'remov1ng the"am-" monia; and subjecting theskins to a fresh tanning action'wlth' 011.

5. In' a process of tanning, the stepsof subjecting thedehaired' skins to the'action of a tanning bath containing c'hroinic aci d then treating the damp skins first with sub turous acid and then with ammonia; remow ing the ammonia; subj ecting the skins to the action of alcohol vapors and then'subme'rg ing themin oil and evap'orating theialcohol, leaving the oil in the'skins to be oxidizedin the presence of the chromium" sesquioxide formed consequent uponthe action of 'the sulfurous acid on the chromic acid, whereby a fresh tanning action is effected.

In testimony whereofI' have signed this specification in the presencebf two subscribmg witnesses.

PIERRE JULREN CLEMENT mama: [L. 5.

\Vitnesses F. Knm'oULLnA'U, MARCELLE BOUILERNE.= 

